The present invention is directed to the total containment welding of plastic tubes. Various prior art exists disclosing different approaches for welding plastic tubes together. The general approach which had been followed by the prior art was to place two tubes across a pair of holders and then cut through the tubes to form two sets of aligned tube sections. One of the sets would then be moved to realign a section from one set with a section from the other set. The realigned tubes would then be welded together.
U.S. Pat. No. 4,753,697 discloses a variation of the prior general approach. In U.S. Pat. 4,753,697 FIGS. 17-20 illustrate a technique wherein each tube in a pair of tubes is folded back toward itself to create a U-shape. A heated wafer is positioned in the space between the bent tubes. The bent tubes are then moved toward each other against the stationary heated wafer. The heated wafer melts sufficiently through the tubes to create four tube sections. The heated wafer is then removed from between the four tube sections and the aligned tube sections are welded together.
The above parent applications describe an improvement over the techniques illustrated in FIGS. 17-20 of U.S. Pat. No. 4,753,697. This improvement involves a melt/wipe process wherein there is simultaneous movement of the heated wafer through the gap between the tubes as the tubes are moved toward each other. Thus, the moving wafer melts the tubes as it wipes across them.
Parent applications Ser. No. 604,979 and Ser. No. 682,977 relate to the techniques wherein each tube is folded toward itself to form a U-shape. Parent application Ser. No. 764,249 discloses a variation of those techniques wherein there is no bending of the tube. The reason for avoiding the tube bending is the concern that in the inner portion of the bight where the tubes are bent, bacteria will exist which will not be killed during the melt/wipe process. By avoiding a bending of the tubes there is no inner bight portion where bacteria can survive.